This invention relates to vapor-jacketed vessels, particularly to a steam-jacketed cooking utensil having a highly efficient, self-contained, gas-fired combustion system.
Steam-jacketed kettles are used extensively in commercial and institutional kitchens. A major feature of such kettles is a cooking surface which can be maintained at or near a constant cooking temperature. The steam-jacketed kettles are available in a variety of sizes (from about 5 to 120 gallons) and are either stationary or may tilt to facilitate removal of food.
Typical steam-jacketed kettles are heated either electrically, as described for example in U.S. Pat. No. 4,145,604, or have separate gas-fired boilers. Other heating arrangements have been proposed, such as the fired-tube vapor generator or wickless heat pipe set forth in U. S. Pat. No. 4,343,292.
Self-contained, gas-fired steam-jacketed kettles are generally large, having a capacity of 40 to 120 gallons. Smaller (5 to 20 gallon) tabletop or wall-mounted kettles are available, but typically only as self-contained, electrically heated units or in a gas-fired "battery" configuration. The electrically-heated units have relatively low heating efficiency and slow response. The "battery" type, which employ a large gas-fired boiler to produce steam for a number of kettles, have the drawback that their boiler must generate steam even if only a single unit is in operation. Also, a breakdown of the boiler renders all of the kettles unusable.
Accordingly, it is an object of the invention to provide a vapor-jacketed cooking utensil having a self-contained heating system of high efficiency.
It is an object of the invention to provide a vapor-jacketed kettle with a compact, self-contained, gas-fired heating system.
It is also an object of the invention to provide a steam-jacketed kettle having a self-contained heating system which provides significant amounts of heat through both radiation and convection.
It is an object of the invention to provide a heating system for a steam-jacketed kettle which permits rapid heatup of the kettle.
It is a further object of the invention to provide a gas-fired heating system for a steam-jacketed kettle whose exhaust products contain low levels of NO.sub.x and CO.